Magnetic Field Angle Sensor Bridge Structure Reduces Harmonic Errors
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Solution Overview
Problem
Magnetic field angle sensors using GMR and TMR elements face angle errors due to phenomena like spin flop and anisotropy, especially at high magnetic fields, which affect the accuracy of angle measurements.
Innovation Solution
A magnetic field angle sensor design incorporating a bridge structure with sine and cosine bridges, each comprising multiple magnetoresistance elements arranged in series and parallel configurations, to generate sinusoidal and cosinusoidal signals, which are then averaged to reduce angle errors by canceling out harmonic errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If GMR or TMR elements are used in angle sensors, then sensitivity is improved, but angle error increases due to spin flop and anisotropy phenomena at high magnetic fields
Solution Approach 1:
The patent divides a single magnetoresistance element into multiple segmented elements (first, second, third, and fourth magnetoresistance elements) with different reference directions. Each segment responds to magnetic fields from different angular positions, and their combined output cancels out harmonic errors and spin flop effects, thereby maintaining high sensitivity while improving angle measurement accuracy at high magnetic fields.
2Measurement precision
If multiple magnetoresistance elements with different reference directions are used, then angle error is reduced through averaging, but device complexity increases
Solution Approach 1:
The patent combines multiple magnetoresistance elements into integrated bridge structures (sine bridge and cosine bridge) that process signals collectively. The first and second elements form one bridge while the third and fourth elements form another bridge, with both bridges working together to generate orthogonal signals. This merging approach simplifies the overall system architecture while achieving error cancellation through the coordinated operation of multiple elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed design significantly reduces angle errors by averaging signals from multiple bridge structures, improving the accuracy of magnetic field angle measurements across a wider range of magnetic fields.
Implementation Method 1
Some magnetic field sensors include magnetoresistance (MR) elements, such as giant magnetoresistance (GMR) elements and tunneling magnetoresistance (TMR)
Data Source
AI summary
In one aspect, a magnetic field angle sensor includes a bridge structure that include a sine bridge configured to generate a sinusoidal signal indicative of a magnetic field along a first axis and a cosine bridge configured to generate a cosinusoidal signal indicative of the magnetic field along a second axis that is orthogonal with respect to the first axis. One of the sine bridge or the cosine bridge includes a first set of at least two magnetoresistance elements, a second set of at least one magnetoresistance element, a third set of at least one magnetoresistance element and a fourth set of at least one magnetoresistance element. An average reference direction of the first set of at least two magnetoresistance elements is equal to an average reference direction of the third set of at least one magnetoresistance element. An average reference direction of the second set of at least one magnetoresistance element is equal to an average direction angle of the fourth set of at least one magnetoresistance element.